A Phase 2 interventional study of Carbon Dioxide and Mechano-acoustic device in Exercise-Induced Vocal Cord Dysfunction, Paradoxical Vocal Fold Motion and Vocal Cord Dysfunction, sponsored by Indiana University. Recruiting at 1 site in United States. Open to participants aged 18 Years to 26 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-11-09.
Sponsored by Indiana University · Phase 2, Interventional, and Other
The overall objectives of the proposed research are to:
The main study will enroll 60 participants with EILO and 60 without EILO to complete three separate visits:
Main Study
At the first study visit, participants will sign informed consent, complete study questionnaires, have their height, weight, and body composition measured, and perform resting pulmonary function tests. Participants will then warm up on the treadmill for 10 minutes. An endoscope will be placed in one nostril until the vocal folds are visible, and subjects will be fitted with a chest strap heart rate monitor, an oro-nasal face mask, and the mechanoacoustic device. This sensor is placed on the neck with a velcro band. Participants will then undergo a graded exercise test during which a carbon-dioxide enriched gas mixture will be administered. The amount of the gas mixture will be titrated based on measures of the participant's breathing and lung function. This visit will be video recorded.
At the second study visit, participants will be asked to again wear the mechanoacoustic device while free running for 10 minutes in a large room or on a track. This visit will be video-recorded.
At the third study visit, participants will be asked to undergo an MRI scan, during which they will perform a variety of breathing exercises including rest breathing, rapid breathing, pursed lip breathing, sniff, and open mouth breathing. Research personnel will instruct participants in the various breathing techniques prior to the scan.
The study visits may occur in any order.
18 studies on the registry are indexed under Vocal Cord Dysfunction; 4 are open to participants now.
Browse Vocal Cord Dysfunction studies →Indiana University is the lead sponsor of 986 studies on the registry; 198 are open to participants now.
Of its 148 completed or terminated interventional studies of FDA-regulated products, 118 (80%) have results posted.
Counted across the registry records on this site, refreshed daily.
The criteria were revised on the registry on Nov 9, 2026. See what changed
Inclusion Criteria for Exercise-Induced Laryngeal Obstruction (EILO):
Inclusion Criteria for Controls
Exclusion Criteria for EILO:
Exclusion Criteria for Controls
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants without Exercise-induced laryngeal obstruction (EILO).
Drug: Carbon Dioxide · Device: Mechano-acoustic device
Drug: Carbon Dioxide · Device: Mechano-acoustic device
Breathing Hypercapnic Gas (10% CO2 (carbon dioxide) and 21%O2 (oxygen), balance N210% (nitrogen))
A custom developed mechanoacoustic sensor will be worn on the neck using a Velcro strap. The device will collect audio recordings of breathing and breath sounds and will collect muscle activity from the neck muscles.
Device measurements from real time running
Muscle activation of cricothyroid/sternohyoid muscle measured via customized surface electromyography amplifier
Time frame: Baseline and Periprocedural
Device measurements from real time running
Normalized amplitude (100% of maximum voluntary contraction) Burst duration (milliseconds) prior to and during Exercise-Induced Laryngeal Obstruction event of laryngeal closure.
Time frame: Baseline and Periprocedural
Device measurements from real time running
Exercise-Induced Laryngeal Obstruction signature detected via ultra-low noise micro-electromechanical (MEMS) microphone amplitude (dB) prior to and during EILO. EILO signature detected via accelerometer (g, where g represents the gravitational acceleration of 9.8 m/s2) prior to and during EILO
Time frame: Baseline and Perioprocedural
Treadmill testing
Breathing frequency (breaths per minute)
Time frame: Baseline and Perioprocedural
Treadmill testing
Tidal volume (Liters)
Time frame: Baseline
Treadmill testing
Ventilation (Liters/minute)
Time frame: Breath-by-breath baseline and Perioprocedural
Treadmill testing
Partial pressure of arterial carbon dioxide estimated from end-tidal partial pressure of carbon dioxide; PetCO2) (mmHg)
Time frame: Baseline and Periprocedural
MRI Upper Airway Size
Length (mm), width (mm), and cross-sectional area (mm2) of oropharynx, supraglottis, glottis, immediate subglottis.
Time frame: Baseline
Upper Airway Aerodynamics
pressure (Pa) across oropharynx, supraglottis, and subglottis
Time frame: Baseline and Periprocedural
Upper Airway Aerodynamics
volume flow rate (l/s) across oropharynx, supraglottis, and subglottis
Time frame: Baseline and Periprocedural
Upper Airway Aerodynamics
flow velocities (m/s) across oropharynx, supraglottis, and subglottis
Time frame: Baseline and Periprocedural
Self-rating of dyspnea
Participants will rate breathing intensity and breathing unpleasantness on a Visual Analog Scale of 0 to 100mm, where 0 indicates not at all and 100 indicates maximal imaginable intensity/unpleasantness.
Time frame: Baseline
Profile of Mood States (POMS)
The POMS will be used to evaluate the participants' mood and to better understand how the emotional state relates to physical responses during testing. The POMS measures different aspects of mood on a 5-point Likert scale from 0 (not at all) to 4 (extremely).
Time frame: Baseline
Menstrual Screening Questionnaire
Female participants will complete a screening questionnaire about menstruation history and use of hormonal birth control which will be used to evaluate the relationship between EILO and menstruation.
Time frame: Baseline
Pittsburgh Sleep Quality Index (PSQI)
The PSQI will be used to evaluate the relationship between sleep and exercise. Total PSQI scores range from 0 to 21 with lower scores indicating better sleep quality.
Time frame: Baseline
International Physical Activity Questionnaire (IPAQ)
Participants will complete the IPAQ which collects information on the frequency and duration of physical activities.
Time frame: Baseline
Plan to share: Yes — The data will be available indefinitely, as per NIH's Data Management and Sharing Policy to maximize the appropriate sharing of scientific data.
Supporting information: Study protocol, Statistical analysis plan, Clinical study report, Analytic code
No publications or documents are linked to this record.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Studies of the drug tested here: Carbon Dioxide